Mechanical Knowledge

Q1. A stone is thrown vertically upwards and its reaches back to ground after 5 seconds find 'u' and the max height stone will attain. Solution:                              s = ut + 1/2 at^2                    0 = u(5) + 1/2(-9.81)(5)^2                                       (9.81/2)(5×5/5) = u                    u = 4.905×5                    u= 24.55 m/sec Now we find maxi height                       V^2 = u^2 + 2as                        0   = (24.55)^2 + 2(-9.81)s                     ...

Thermodynamics  Chapter: First law of Thermodynamics  Question 2. An insulated pressure vessel divided into two parts. One part of vessel is occupiedby an ideal gas at a pressure P1, volume V1 & temp T1.The other part occupied by the same gas at a pressure P2, volume V2, & temp T2. The partition is removed and the two parts are mixed. Then show that the final pressure P3 & final T3 is   Solution:  Same ideal gas  PV = mRT   ...................................................................(1) Mass Conservation : m1+m2 = m3      ......................................(2) Energy conservation: m1 u1 + m2 u2 = m3 u3                                       m1 Cv T1 + m2 Cv T2 = m3 Cv T3                                 m1 T1 + m2 T2 = m3 T3 Use PV =...

THERMODYNAMICS CHAPTER: FIRST LAW OF THERMODYNAMICS Question 1. Air at initial temp of 300K & initial volume of 0.002 m^3 is contain in a piston cylinder arrangement. Initially a spring is attached to the piston having a spring constant of 10 kN/m is touching the piston but no force exerting on it. Now heat is added to the air & it expended slowly to occupy a final volume of 0.03 m^3 and the area of piston is 0.02 m^2. The atmospheric pressure assume to be 100KPa. Then determine the final pressure inside the cylinder. Solution  T1 = 300K V1 = 0.002 m^3  V2  = 0.03 m^3 Spring constant (K) = 10 KN/m A = 0.02 m^2 Patm = 100 KPa  Psp = pressure applied by spring Patm = pressure applied by atmosphere P1 = inside pressure of piston at position one  P2 = inside pressure of piston at position two   P1 =  Patm + Psp1   ……………..............................(0)                        ...

THERMODYNAMICS  CHAPTER: ZEROTH LAW OF THERMODYNAMICS Question 3. What does a temperature difference of 10 on °C scale corresponding toon a Fahrenheit scale. Solution:-                            Δtc = 10              (:: Δ= d/dt) We know     tf = 9/5tc + 32   ....................(0) Applying Δ on both sides of equation (0),                            Δtf  = 9/5Δtc   ....................(1)                                                                      (:: here 32 is zero because it is constant   Put Δtc = 10  in equation (1)              ...

THERMODYNAMICS QUESTION SOLUTION, CHAPTER. ENERGY INTERACTION. Question 1. A spherical balloon of 1m diameter contains a gas at 150 KPa. The gas inside balloon is heated until pressure reaches 450 KPa. During the process of heating the pressure of gas inside the balloon is proportional to cube of the diameter of the balloon. Find the work done by the gas. Solution: D1= 1 m    P1= 150 KPa                                           V = (4/3)  π R^3 =    πD^3/6        P2 = 450 KPa                                             dV = ( π/6)  (3D^2)    δD P directly proportional D^3                         dV = ( π/2) (D^2)   δD P = k(D^3) ...

 Q1. If LSU has no tin ball what we have to do. (a) confirm is ball need to fill  (b) add tin ball (c) move solder nozzle (d) none of the above Ans: (a) Q2. Which command we have to use if computer screen shows tester is running in background. (a) alt+tab+esc (b) shift+ctrl+esc (c) ctrl+shift+esc (d) esc+shift+ctrl Ans (c) Q3. What are the benefits of nitrogen in soldering? (a) Better wetting (b) less heat (c) both A and B (d) none of the above Ans (c) Q4. What are the measure concern when clean a laser lens? (a) follow steps (b) make sure nitrogen and air pressure is not on (c) take some time (d) all of the above Ans (b) Q5. How much approximate pressure need before to spray ball on module (a) 1722mbar (b) 1500mbar (c) 1054mbar (d) 2001mbar Ans (c) Q6. How many main pressure gauges in soldering machine? (a) 5 (b) 7 (c) 8 (d) 2 Ans (d) Q7. What is the meaning of number1 blue color at the time soldering process on HMI screen? (a) module is not there (b) module is there or modul...

 Q1. Which of the following case soldering nozzle is block? (a) Laser center is not correct (b) Module lift up before soldering (c) Ball center is not correct (d) None of these Ans (b) Q2. Which switch used to move socket at CCD position (a) Positioning camera (b) Positioning location (c) Move (d) All of the above   Ans (a) Q3. How many levels ball need to fill in soldering?  (a) Half (b) Full (c) Semi half (d) none of these Ans (a) Q4. What metal is the solder ball made of  (a) iron (b) tin (c) Both A and B (d) None of these Ans  (b) Q5. what should we do, if jig did not sense by left and right station? (a) Check jig is placed flat (b) Check proximity sensor of the center fixture is loose or offset  (c) Check jig and press emergency  (d) All of the above Ans (a) Q6. What we have to do if computer screen shows us image timeout. (a) Press emergency (b) Restart the CCD positioning camera (c) Press home s...